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Title: Gate dielectric degradation: Pre-existing vs. generated defects

We consider the possibility that degradation of the electrical characteristics of high-k gate stacks under low voltage stresses of practical interest is caused primarily by activation of pre-existing defects rather than generation of new ones. In nFETs in inversion, in particular, defect activation is suggested to be associated with the capture of an injected electron: in this charged state, defects can participate in a fast exchange of charge carriers with the carrier reservoir (substrate or gate electrode) that constitutes the physical process underlying a variety of electrical measurements. The degradation caused by the activation of pre-existing defects, as opposed to that of new defect generation, is both reversible and exhibits a tendency to saturate through the duration of stress. By using the multi-phonon assisted charge transport description, it is demonstrated that the trap activation concept allows reproducing a variety of experimental results including stress time dependency of the threshold voltage, leakage current, charge pumping current, and low frequency noise. Continuous, long-term degradation described by the power law time dependency is shown to be determined by the activation of defects located in the interfacial SiO{sub 2} layer of the high-k gate stacks. The findings of this study can direct process optimizationmore » efforts towards reduction of as-grown precursors of the charge trapping defects as the major factor affecting reliability.« less
Authors:
;  [1]
  1. SEMATECH Inc., 257 Fuller Rd., Albany, New York 12203 (United States)
Publication Date:
OSTI Identifier:
22275685
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHARGE CARRIERS; CHARGE TRANSPORT; CRYSTAL DEFECTS; DIELECTRIC MATERIALS; ELECTRIC POTENTIAL; ELECTRON CAPTURE; ELECTRONS; LAYERS; LEAKAGE CURRENT; PHONONS; SILICON OXIDES; STRESSES; SUBSTRATES